A US military assessment found the main part of the missile landed approximately 35 kilometers (22 miles) from Pukchang airfield, a US official told CNN.

South Korean officials said the test likely was a failure.

"We are analyzing additional information," the nation's Joint Chiefs of Staff said. "Our military is maintaining a thorough defense posture while keeping a close eye on the possibility of North Korea's further provocations."

White House officials said President Donald trump was briefed as Air Force One returned to Maryland from Atlanta, where Trump earlier addressed a meeting of the National Rifle Association.

The test-fired missile probably was a medium-range ballistic missile called a KN-17, the US official said. The KN-17 is a land-based solid-fuel missile fired from a mobile launcher.

There has been no announcement on North Korean state television, CNN's Will Ripley in Pyongyang reported.

It is North Korea's ninth attempted missile launch -- by CNN's count -- since Trump became President in January. Some of those missiles reached the the Sea of Japan, also known as the East Sea, but Saturday's test apparently did not.

The launch came hours after US Secretary of State Rex Tillerson addressed a special meeting at the United Nations, calling for increased pressure on North Korea.

"All options for responding to future provocations must remain on the table," Tillerson said. "Diplomatic and financial leverage or power will be backed up by willingness to counteract North Korean aggression with military action, if necessary."